Subsea wells normally have a wellhead housing, which is a large tubular member located at the sea floor. Casing will be supported in the wellhead housing by a casing hanger. During drilling, a riser will extend upward from the subsea wellhead housing to a floating platform. A wellhead connector will connect the lower end of the riser to the wellhead housing.
A wellhead connector bolts to the lower end of the blowout preventer (BOP) stack, which is run at the bottom of the riser. The upper body of the wellhead connector is attached to the lower body through bolts which extend through of the upper body into the lower body assembly. The lower body assembly has a cylindrical portion that extends around the wellhead housing. The upper body has a downward facing shoulder that lands on the upper rim of the wellhead housing. A seal is located at the shoulder between the wellhead housing and upper body of the wellhead connector.
A locking element, preferably a set of dogs, are pushed out from a retracted position into engagement with an external profile on the wellhead housing.
While this type of connector is workable, large bending moments due to riser tension may cause the connector to move slightly relative to the wellhead is housing. This movement should be minimized.